The present invention relates to a steering system for a motor vehicle having a lower steering spindle which is divided into two steering spindle parts which are connected with one another by way of elastic damping devices.
In known steering systems for motor vehicles, jolts and vibrations which affect the steering system from the road are damped by flexible disks. In addition, axially displaceable elements are provided to compensate for steering bolster movements. Such axially displaceable elements are also used in longitudinally adjustable steering columns.
DE 28 55 524 A1 describes a steering system having a lower steering spindle which is divided into two steering spindle parts. The two steering spindle parts are connected with one another by a steering coupling which, for achieving a sufficient steering elasticity, has torsionally elastic coupling elements. In addition, a torsional damper is integrated in the steering coupling which can absorb disturbing vibrations. However, axial relative movements cannot be compensated.
It is an object of the present invention to provide a steering system which, by simple and compact devices, ensures an axial compensation as well as a sufficient steering elasticity.
This object has been achieved in accordance with the present invention in that a rubber-elastic damping block serves as a damping device, and one guide member is assigned to each respective spindle part and projects freely along the spindle axis. The guide members of the opposite spindle parts are disposed in an oppositely axially displaceable manner in corresponding guide receiving devices of the damping block. The axial displaceability of the guide members within the guide receiving devices is limited by axial securing devices assigned to each spindle part.
As a result of the features of the present invention which achieves a compact constructional unit, a sufficient radial steering elasticity as well as an axial displaceability of the two spindle parts relative to one another is implemented. By the providing only a single constructional unit, fewer components are required in comparison to conventional arrangements. In addition, the steering system has a reduced weight, and, because of this constructional unit, the steering system can be manufactured, mounted and demounted at much lower cost and effort.
As a further feature of the invention, the damping block has a cylinder-shaped configuration and is enclosed by a hollow-cylindrical housing sleeve in which the guiding members and the axial securing devices are also arranged. The constructional unit therefore forms a torsionally elastic and axially movable coupling between the two spindle parts, in which the housing sleeve is used as a coupling housing.
Another aspect of the present invention is that at least four passage ducts are integrated in the damping block which are used as guide receiving devices and which are arranged parallel to one another at uniform distances on a common circular line which is concentric with respect to the longitudinal center line. From opposite sides of the passage ducts a corresponding number of guide pins project into the passage ducts and are used as guide members whose length is larger than the length of the passage ducts. As a result, an axial displaceability is achieved while the axial guiding remains uniform. Because at least two guide pins are assigned to each spindle part, a reliable, rotationally locking drive is also achieved by way of the damping block.
According to yet another aspect of the present invention, the two or more guide pins for each respective spindle part are held in a radial guide disk which is disposed inside the housing sleeve in an axially linearly movable manner and which is fixed on the respective spindle part. Thereby, an operationally reliable connection is established between the spindle parts and the guide pins.